This invention relates to optical coupling arrangements and more especially to such arrangements for coupling separate modules in electronic multiprocessor systems.
Such modular systems require internal communications between the separate modules. This communication generally takes place via a bus coupling the modules and has usually been via an electrically conducting bus.
In a number of applications it is desirable that the modules be in communication with each other but electrically isolated from each other so as to minimise electromagnetic induction effects. Such galvanic isolation has been achieved in the prior art in numerous ways. For example, it is known to use infrared communication, as in a TV remote control system, or to use optical communication as in some types of personal computer keyboards.
It is well known to use optical communication as a means of electrically isolating separate modules and this communication has hitherto been achieved via optical fibers.
In one such system a multi-drop optical fiber is used as a bus with directional couplers inserted at every drop point transmitting the signal to each photodetector.
Such optical fiber buses are however difficult to alter since their configurations are fixed by the number of directional couplers provided.